Investigations on geometrical features in induced ordering of collagen by small molecules

Journal of Chemical Sciences (Impact Factor: 1.22). 01/2003; 115(5):751-766. DOI: 10.1007/BF02708265

ABSTRACT Binding energies of the interaction of collagen like triple helical peptides with a series of polyphenols, viz. gallic acid,
catechin, epigallocatechingallate and pentagalloylglucose have been computed using molecular modelling approaches. A correlation
of calculated binding energies with the interfacial molecular volumes involved in the interaction is observed. Calculated
interface surface areas for the binding of polyphenols with collagen-like triple helical peptides vary in the range of 60–210
Å2 and hydrogen bond lengths vary in the range of 2.7–3.4 Å. Interfacial molecular volumes can be calculated from the solvent
inaccessible surface areas and hydrogen bond lengths involved in the binding of polyphenols to collagen. Molecular aggregation
of collagen in the presence of some polyphenols and chromium (III) salts has been probed experimentally in monolayer systems.
The monolayer arrangement of collagen seems to be influenced by the presence of small molecules like formaldehyde, gluteraldehyde,
tannic acid and chromium (III) salts. A fractal structure is observed on account of two-dimensional aggregation of collagen
induced by tanning species. Atomic force microscopy has been employed to probe the topographic images of two-dimensional aggregation
of collagen induced by chromium (III) salts. A case is made that long-range ordering of collagen by molecular species involved
in its stabilisation is influenced by molecular geometries involved in its interaction with small molecules.


Available from: Balaraman Madhan, Jun 04, 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Electrospun chitosan fibers have numerous potential in biomedical, food, and pharmaceutical applications. However, the mats formed are often not chemically stable in a wide range of pHs unless crosslinked. Here, we report on the use of glycerol phosphate (GP), tripolyphosphate (TPP) and tannic acid (TA) as a new set of non-covalent crosslinkers for electrospun chitosan fibers. Crosslinking with or without heat or base activation were performed either prior to (one-step or activated one-step) or after (two-step or activated two-step) electrospinning with either GP or TA. TPP crosslinking was performed in two-step and activated two-step. FESEM, FTIR and UV-vis transmittance at 600nm were used to determine fiber surface morphology, chemical interactions and solubility in 1M AA (pH 3), water (∼pH 6) and 1M NaOH (pH 13), respectively. Crosslinking of chitosan with GP and TA yields fibers with a mean diameter range of 145-334nm and 143-5554nm, respectively. TPP crosslinking produced branched fibers with mean diameters of 117-462nm range. Two-step chitosan-TA did not dissolve in 1M AA even after 72h while all chitosan-TPP, activated two-step chitosan-TA and two-step heat activated chitosan-GP fibers survived in water after 72h.
    06/2013; 95(1):123-33. DOI:10.1016/j.carbpol.2013.02.034
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Identifying the molecular interactions using bioinformatics tools before venturing into wet lab studies saves the energy and time considerably. The present study summarizes, molecular interactions and binding energy calculations made for major structural protein, collagen of Type I and Type III with the chosen cross-linkers, namely, coenzyme Q10, dopaquinone, embelin, embelin complex-1 & 2, idebenone, 5-O-methyl embelin, potassium embelate and vilangin. Molecular descriptive analyses suggest, dopaquinone, embelin, idebenone, 5-O-methyl embelin, and potassium embelate display nil violations. And results of docking analyses revealed, best affinity for Type I (- 4.74 kcal/mol) and type III (-4.94 kcal/mol) collagen was with dopaquinone. Among the selected cross-linkers, dopaquinone, embelin, potassium embelate and 5-O-methyl embelin were the suitable cross-linkers for both Type I and Type III collagen and stabilizes the collagen at the expected level.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Collagen is an extremely important protein, which provides mechanical strength and structural integrity to various connective tissues. Ramachandran and his coworkers had proposed the triple helical structure for collagen employing fiber diffraction theory with stereochemical consideration. Due to its unique triple helical motif an understanding of the amino acid sequence-dependent stability of polypeptides is of renowned interest to the biophysicists and biochemists, in order to identify the nature of forces that stabilizes the three dimensional structure of proteins. Mutation in collagen genes COL1A1 and COL1A2 leads to Osteogenesis Imperfecta (OI), a brittle bone disease Often a point mutation in one of type I collagen genes can cause disease. Hence it is necessary to probe the stability of collagen upon mutation. In this study, the role of various collagen triplets influencing the stability of collagen has been addressed using various molecular modeling tools. In addition interaction of collagen like model peptides with polyphenol molecules have also been investigated to gain how various small molecules stabilizes the collagen matrix. The importance of geometrical features of polyphenol molecules has also been probed with the help of ab initio and molecular mechanics methods. Bioinformatic analysis has also been attempted on various types of collagen.